Field of the Invention
A first aspect of the invention is related to an auxiliary device for welding broached disks comprising a damping belt and another aspect is related to an associated friction welding method.
Description of the Related Art
Turbojet and turboprop disks are frequently friction welded to each other and particularly by inertial friction in assembly planes perpendicular to the rotation axis of the rotor thus created. They frequently comprise broached slots around their periphery inside which blade roots and possibly blade retaining hooks located at the ends of the slots will be fitted.
This welding method uses very high energy and almost always produces high intensity and high frequency vibrations. Fatigue cracks may then appear at the bottom of the slots, and at the bottom of the blade retaining hooks.
These disadvantages of friction welding are already well known and it has been proposed that they can be corrected by associating elements for damping of these vibrations to the parts to be welded. Documents US 2004/108358 A and 2010/193 572 A disclose a few examples. However, it would seem that the damping devices according to these patents are not adapted to the special case of disks with peripheral slots and do not prevent the development of cracks by vibration fatigue at the most exposed locations, namely at the fillet connections between the peripheral teeth separating the slots and the main part of the disk starting at the bottom of the slots, and at the bottom of the blade retaining hooks. US 2006/051211 discloses a more complex damping element than the element according to the invention comprising two side polymer belts held between two metal end plates, that are brought towards each other to keep the belts on the side faces of the disk. The damping element described in this prior document certainly relates to a disk to be friction welded, but this disk has no broached slots separated by teeth to contain blade roots, because the disk disclosed in this prior document is a single-piece blisk that already carries blades.